1. Field of the Invention
The present invention relates to a tape drive unit and to a recording medium.
2. Description of the Related Art
A so-called xe2x80x9ctape streaming drivexe2x80x9d is known as a drive unit for writing/reading digital data on/from a magnetic tape. This tape streaming drive can have a large recording capacity of, for example, approximately several dozen to several hundred gigabytes, although the capacity varies according to the length of the tape (as a medium) in the tape cassette. Accordingly, the tape streaming drive has various uses, such as a backup of data recorded on a medium such as a hard disk for a computer. The tape streaming drive is suitable for storing image data, which is typically large.
As the above-described tape streaming drive, one that performs data writing/reading by employing a helical scan system using a rotary head and using, for example, an 8-mm videocassette-recorder (VCR) tape cassette as a recording medium, has been proposed.
A tape streaming drive using an 8-mm VCR tape cassette, as described above, uses, for example, a small computer system interface (SCSI) as an input/output interface for data to be written/read.
In the writing mode, data supplied from, for example, a host computer, are input via the SCSI interface. Predetermined compression and encoding processes on the input data are performed and the processed data are recorded on a magnetic tape in a tape cassette.
In the reading mode, the data on the magnetic tape are read and decoded. The decoded data are transmitted to the host computer via the SCSI interface.
When data are recorded on or reproduced from a magnetic tape, a writing operation or a reading operation is retried as required.
With reference to FIGS. 20A and 20B, an outline of operations performed when data are written on and read from a magnetic tape is described below. FIG. 20A shows the data writing operation, and FIG. 20B shows the data reading operation. In FIGS. 20A and 20B, PBOT means the physical beginning position of the magnetic tape, and PEOT means the physical end of the magnetic tape.
When data #12 is written on the magnetic tape, as shown in FIG. 20A, data #12a is supplied and stored in a predetermined memory of a tape streaming drive. Data #12a is read from the memory and is (1) written by a recording head. Almost immediately after that, data #12b on the magnetic tape is (2) read by a reproducing head. The read data #12b is stored as data #12c in the memory. In the memory, data #12a and data #12c are (3) compared. If both data coincide, the comparison result is regarded as affirmative, which allows the recording of the successive data such as data #13 and data #14 (not shown).
If data #12a and data #12c do not coincide, the comparison result is regarded as negative. In this case, the same data #12a is written again as data #12d, as indicated by the broken line. This recording operation is called xe2x80x9cwrite retry by read-after-writexe2x80x9d.
When data #12 recorded on the magnetic tape is read, as shown in FIG. 20B, if data #12 is not successfully read based on a predetermined error-detecting process, etc., in other words, the result of reading is regarded as negative, read retry is performed.
The read retry is performed by (4) reading the magnetic tape while scanning the magnetic tape from its beginning, and continuously performing the reading when the result of reading data #12 is regarded as affirmative. If the result of reading data #12 is regarded as negative, the reading operation is halted and (5) a reading position return is performed from the halting position, and data #12 is read again by (6) running the magnetic tape from the position obtained by the reading position return.
In the following description, simply using xe2x80x9cretryxe2x80x9d means both write retry and read retry.
As described above, by performing retry so that error generated in the recording/reproducing mode is reduced, precision of data can be increased.
Nevertheless, when real-time sequential data (image data), such as a movie, are recorded, a case may be generated in which actual recording cannot be performed because an actual recording operation is interrupted by performing write retry.
In addition, when data recorded along real time are reproduced, the execution of read retry hinders reading while (5) the reading position return or (6) the magnetic tape running is performed. This may generate a case where the real time of the image data is fragmented.
Accordingly, it is possible to inhibit retry in accordance with the type of data treated by the tape streaming drive. However, at the time a tape cassette is loaded into the tape streaming drive, an operation mode adapted for the use of the tape cassette, i.e., retry (write and/or read) inhibition or permission, must be set.
The set operation mode (retry permission/inhibition) is stored in the memory of the tape streaming drive. Thus, when the loaded tape cassette is exchanged, an operation mode adapted for another tape cassette must be set again.
Accordingly, it is an object of the present invention to provide a tape drive unit and a recording medium in which the setting of retry-permission/inhibition is easily performed.
To this end, according to an aspect of the present invention, the foregoing object is achieved through provision of a tape drive unit including: a tape driver for writing/reading information on/from a magnetic tape when a tape cassette including the magnetic tape is loaded; a memory driver in which, when the loaded tape cassette includes a memory for storing management information for managing the writing/reading of information on/from the magnetic tape, the memory driver writes/reads the management information in/from the memory; a detecting unit for detecting retry-permission/inhibition information (stored in the memory) instructing a permission or inhibition to retry the writing/reading of information on/from the magnetic tape; and an operation-mode setting unit for setting the operation mode of the tape driver, based on the retry-permission/inhibition information.
According to another aspect of the present invention, the foregoing object is achieved through provision of a tape drive unit including: a tape driver for writing/reading information on/from a magnetic tape when a tape cassette including the magnetic tape is loaded; a detecting unit for detecting retry-permission/inhibition information instructing a permission or inhibition to retry the writing/reading of information on/from the magnetic tape, the retry-permission/inhibition information stored in the memory; and an operation-mode setting unit for setting the operation mode of the tape driver, based on the retry-permission/inhibition information.
According to a further aspect of the present invention, the foregoing object is achieved through provision of a recording medium including a tape cassette including a magnetic tape and a memory included in the tape cassette. The memory stores management information for managing writing/reading on/from the magnetic tape. The memory stores retry-permission/inhibition information instructing a permission/inhibition to retry writing/reading on/from the magnetic tape.
According to yet another aspect of the present invention, the foregoing object is achieved through provision of a recording medium including a tape cassette including a magnetic tape. The magnetic tape includes a management information region for storing management information for managing writing/reading on/from the magnetic tape. The management information region stores retry-permission/inhibition information instructing a permission/inhibition to retry the writing/reading on/from the recording medium.
According to the present invention, a tape drive unit can detect retry-permission/inhibition information from a memory, and can set, based on the detected retry-permission/inhibition information, an operation mode as to whether retry is performed for a loaded tape cassette.
The tape drive unit can also detect retry-permission/inhibition information from the information management area a magnetic tape, and can set, based on the detected retry-permission/inhibition information, an operation mode as to whether retry is performed for a loaded tape cassette.
According to the present invention, a recording medium stores retry-permission/inhibition information in a memory thereof. Thus, whenever the recording medium is loaded, a tape drive unit can detect the retry-permission/inhibition information from the memory.
According to the present invention, a recording medium stores retry-permission/inhibition information in the management area of a magnetic tape thereof. Thus, whenever the recording medium is loaded, a tape drive unit can detect the retry-permission/inhibition information from the magnetic tape.
In other words, the retry-permission/inhibition information can be supplied to a tape drive unit adapted for the memory or the magnetic tape.